LinkedList（）实现类

Question

import java.util.List;public class LinkedList { private List ls; LinkedList() { this.ls = new LinkedList();    //为什么这句会报错呢？LinkedList不也是List的实现类吗？ }}

Answer 1

你要 import java.util.LinkedList; 

ll.addFirst() 这个要写参数：

ll.addFirst(new News(2,"a","s"));

Answer 2

没导包!

Answer 3

好不容易弄好了 为什么带不出addFirst(),removeFirst()这些方法？

import java.util.LinkedList;

import java.util.List;

public class LinkedListTest {

private List ll;

LinkedListTest() {

this.ll = new LinkedList();

}

void add() {

ll.add(new News(1,"u","k"));

ll.add(new News(2,"m","z"));

ll.add(new News(2,"a","s"));

ll.addFirst()   //这句编译报错

}

}